KTM Husky 250F Crank Wear

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7/15/2020 12:38 PM
Edited Date/Time: 7/15/2020 3:40 PM

Picking up a used 2017 FC250 with unknown hours (likely 100+).
I fully anticipate framing the bike, and at least replacing the piston, rings, cam chain, and tensioner.
It will most likely get a new oil pump gear, while I have motor out.

With regard to the crank, is it enough to check for run-out/wear by dial indicator, or just split it and replace the rod and bearings to be on the safe side?

If i use the run-out method, does anyone have some good specs for maximum allowable play.

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KTM250SX YZ125 YZ85 PW80 ZX6 FZX700

7/15/2020 2:21 PM

YZed250 wrote:

Picking up a used 2017 FC250 with unknown hours (likely 100+).
I fully anticipate framing the bike, and at least replacing the piston, rings, cam chain, and tensioner.
It will most likely get a new oil pump gear, while I have motor out.

With regard to the crank, is it enough to check for run-out/wear by dial indicator, or just split it and replace the rod and bearings to be on the safe side?

If i use the run-out method, does anyone have some good specs for maximum allowable play.

If it’s not hard for you and or you can afford to replace bearings, you will have a better piece of mind.

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7/15/2020 7:29 PM

100 hours on a 450 calls for a complete top and bottom rebuild to include fully rebuilding the crank. Get a manual and see what the side to side tolerance and check for up and down play and then make your call.

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The older I get, the faster I was.

7/16/2020 6:05 AM

Those KTM cranks are nice pieces. The one in the pic had 120 hours of female mx. A friends wife.
If it were to be trail ridden I would of not rebuilt it for her .
Before disassembly it had run out of .0015 But the side to side clearance to thrust washers was a little loose
I dont recall the measurement. But .032 come to mind.
The cam chain & tensioner definitely need replacement. I also did a piston & rings at 75 hours. & during this rebuild also.

If this was ridden by a fast kid , Change it for piece of mind. FYI the KTM rod kits are pricey. It may make since to buy crank assembly if you cant rebuild it cheaply.
I would worry more about the rod breaking than the plain bearing going bad.
It was trued in V blocks I was just double checking in my lathe . Sometime the crank centers can be off from the bearing surfaces


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7/16/2020 6:11 AM

In general, if youre splitting cases its best to get your crank rebuilt while youre there. Just make the entire bottom end solid.

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7/16/2020 7:06 AM

I would never run a crank past 100hrs. Plenty go much further when pushed but plenty never make it. 89hrs on my son's KTM 65 and I already have a new crank ready to go in in the next few weeks.

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7/16/2020 8:39 AM

160 hours on a factory crank out of a 2016 KTM 150. No play yet, but one of the crank bearings let go. Going to send it out to get rebuilt.

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7/20/2020 10:12 AM

Thanks to all that replied.
Bike has 170hrs and I don't have any reason to doubt it.

It was owned by a Mexican guy in country California who ran it up and down the flat farm roads. There are no trails in his area, and he had no way to bring the bike to tracks or even connect to trails. Fortunately the guy was mostly scared of it after a couple of decent crashes.

The front tire was completely bald from riding on hard/asphalt roads. So yes, the motor will have a full restore, although it sounds amazing tight. My previous 2013 350 KTM made tons of topend noise (cam chain, tensioner) at 100 hours and this bike is amazingly quite compared to that.

Everything external needs some love (tires, levers suspension, chain sprockets, bars), so I think some preventative maintenance will go a long ways.

Considering what I paid for the bike, I can afford to drop $1500 on it and still be doing ok. Should be a fun little project and thanks again.

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KTM250SX YZ125 YZ85 PW80 ZX6 FZX700

7/20/2020 10:15 AM

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KTM250SX YZ125 YZ85 PW80 ZX6 FZX700

7/20/2020 4:24 PM

It's crazy how people can spend so much money on a bike just to treat it like this. Looks like it should be a good project, That's my favorite Husky gen.

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7/20/2020 4:25 PM

Start a build thread for your progress!

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7/20/2020 7:13 PM

Rickyisms wrote:

Start a build thread for your progress!

Not planning to go cerrakote /ti bolts/the whole 9 yards on this thing, but I will take some pics as I go in case it turns into something I am proud of/think it’s worth sharing. Right now it’s just a rat and hoping to turn it into the capable racer I know it can be. Will know more once I dive into the motor.

If things don’t look good, it will be parted out/flipped in short order. Been Around too long to get too attached to something that will be outdated in 5years. But it does have a classic look that has me reading those cerrakote Ti and carbon build threads on vital wishing I had more time and money to sink into her cool

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KTM250SX YZ125 YZ85 PW80 ZX6 FZX700